1. Technical Field
The present invention relates to a display system, a screen and a projector.
2. Related Art
Hitherto, there is known a technique in which an image is displayed on a screen by a projector or the like. In recent years, a technique is proposed in which an image light is diffused and scattered by a transparent screen and an image is displayed. When this technique is used, a person or a physical body in an actual space where the screen is arranged is observed through the screen, and the image can be assimilated to the actual space.
For example, when information relating to a window-displayed exhibit is projected on the window glass, the information can be effectively displayed without disturbing the observation of the exhibit. At a bank window or the like, when information of a visitor is displayed to a receptionist side, or information of the receptionist is displayed to the visitor side, the counter work can be smoothly handled. In a television conference or unattended reception, when an image in which only a person is selected is projected, reality can be provided as if the person exists.
As stated above, when the transparent screen is used, an image can be displayed while the observer does not feel the existence of a device of a display, and the effective information provision and image presentation with high presence can be performed. As the transparent screen, those disclosed in JP-A-2000-75139 (patent document 1) and JP-A-6-82748 (patent document 2) are cited. The patent document 1 proposes a manufacturing method of a hologram screen on which a pattern obtained by interference between reference light of non-diffused light and object light diffused from a light diffusion body is recorded. The patent document 2 proposes a screen in which transmission and scattering can be switched by a liquid crystal layer.
The screen is required to be capable of displaying a high quality image, and further, the transparent screen is expected to have improve transparency from the viewpoint of erasing the display from consciousness. In the techniques of the patent documents 1 and 2, there is a problem to be improved in view of compatibility between the image quality and the transparency.
In the hologram screen of the patent document 1, the interference pattern between the reference light and the object light is recorded. Thus, when a viewing angle is made wide, since the transparency is degraded and the screen itself is observed, the presentation effect decreases. When the transparency is raised, since the viewing angle is narrowed and it becomes hard to observe the image, the image quality is deteriorated.
In the liquid crystal screen of the patent document 2, when a unit area where transmission and scattering are switched is driven by an active element such as a TFT, the active element becomes a reflection and scattering medium. Thus, the transparency is degraded. When the unit area is passive driven and the active element is not arranged on the screen, the number of scanning lines is at most four because of the VT threshold characteristic of the scattering liquid crystal. Then, the unit area to switch the transmission and scattering has a remarkably low resolution as compared with the image, and the periphery of the image becomes a large scattering area, and accordingly, the transparency is degraded.